1. Field of the Invention
The present invention relates to a zoom lens that is small in size and suitable for a camera with a lens shutter or a video camera.
2. Background Arts
A camera with a lens shutter conventionally uses a zoom lens consisting of a front lens group having a positive power and a rear lens group having a negative power. As an example of small size zoom lens consisting of two lens groups, JPA 3-158815 discloses a zoom lens whose front lens group consists of two lens elements and whose rear lens group consists of a single lens element. In this zoom lens, the first and second lenses of the front lens group are spaced from each other by a relatively long distance in order to balance various aberrations well.
Indeed the zoom lens of the prior art uses merely three lens elements, but the larger spacing between the two lenses of the front lens group makes the total length of the zoom lens relatively large even in its retracted or collapsed position. Moreover, as the spacing between the two lens of the front lens group increases, the first lens must have a larger effective aperture and thus a larger diameter. As a result, also the diameter of the zoom lens of the prior art is relatively large.